Basal part of  the  Shemshak  group  in Galandrud  area ,  in  north  Alborz  about 16 km  south of  Ruian city (Alam- Deh)  was  investigated  palynologicaly.  The studied  section  attains  a thickness of  590  meters  and  consists of  limestone,  shale ,  sandstone   and   siltstone  beds.   A  total  of  29  samples  were  selected  and  treated  in  the palynological   laboratory of the  geological survey  of  Iran.  Eighty  one  palynomorph  taxa  were  encountered .   The recorded   dinoflagellate  species   were  arranged   in  four  local  bioassemblage  biozones  and a superbiozone (Rhaetogonyaulax).
Biozone I;  Heibergella  asymmertrica,  occurs in  a  thickness  of  60  m , suggesting an Early Norian age.
Biozone II ;  Heibergella  aculeata,  occurs  within  50m ,  representing  a  Middle  Norian  age.
Biozone III ;  Hebecysta balmei, which occurs in a thickness of 40 m, indicating the Middle to Late  Norian age.
Biozone IV;   Rhaetogonyaulax  rhaetica  , occurs  in  a  thickness  of  330 m,  indicating  a Late  Norian  to Rhaetian age.
Statistical  studies  on the  recorded palynomorph  assemblages show that  lower parts of the section have been deposited  in an  open  marine  environment.  In  Late  Norian a  regression  of  the  sea   caused  sediment  of  the Rhaetian  to  be  deposited  in  a  deltaic  environment  .  The   Early  Kimmerian  and  the  following  orogenic  phases  have   had   the  least  effected  on  the sedimentation  processes during  Late Triassic  age  in  this area  and the carbonaceous  Elika  Formation turned into Shemshak group gradually and without any disruption.